Star NightSky *by Zero Centre is a beautiful chain reaction game for your iPhone.
If you have played an old favorite, Splode, then you will immediately understand how to play Star NightSky. However, I will explain the concept for the uninitiated – simply tap on the screen to trigger a chain reaction, and clear out the minimum requirement to move on to the next level.
Star NightSky is a puzzle game that takes timing and skill to do well in (as like all other puzzle games). There are two modes: Challenge and Time.

Challenge is the basic mode that will have you clearing out a certain amount of stars before you can move on to the next level. Simply tap on the screen to trigger a ripple – this ripple will cause stars that touch it to grow (and spin wildly) and also gets you points for each star. Any other stars that touch the expanded stars grow as well, starting the chain reaction. The stars only expand for a short amount of time, so if there are no more stars for the chain, it will end. If the chain ends without meeting the minimum amount of stars to clear the level, then you lose one of your five lives.
The other neat aspect of Challenge is that there are new stars that get introduced every few levels, which have various effects that can help you pull off chains easily. The game will introduce you to each type of star by showing what it looks like as well as what it does. Make sure to use these to your advantage.
Challenge mode starts off easy, but it gets increasingly difficult as you continue. Rather than seeing less than 10 stars on the screen at once, you’ll end up with more than 60, and you will have to time your taps correctly in order to achieve the biggest chain possible.
In Time Mode, you have a certain amount of time which is denoted at the top left corner of the screen, where it says “Time.” You will notice that the extended line will get shorter, like a bomb fuse (which is exactly what it is, really). You won’t have a lot of time, so set off the chain reaction as quickly as you can. With each successful chained star, you will extend the time as well as gain points. The point of this mode is basically just make a chain reaction happen long enough to keep extending your remaining time.